PROJECT SUMMARY This K01 proposal, ?mHealth Intervention via Mentors: Preventing Substance Use, Sexual Risk, and Violence among Inner City Baltimore Youth through Technology-Enhanced Mentoring,? addresses two fields of study relevant to adolescent health that deserve further attention, particularly in how they can intersect to improve public health: youth mentoring and mobile health (mHealth) prevention interventions. Adolescents growing up in low-income urban areas such as Baltimore are at particularly high risk for unhealthy practices such as substance use, sexual risk, and engagement in violence. For adolescents who lack socially protective resources such as parents, attentive teachers, or community networks, mentors can play a significant role in helping to reduce stress, prevent negative health behaviors, and model positive health behaviors. However, little is known about the pathways by which mentee health behavior change occurs, especially for the prevention of substance use, how matched mentors can effectively communicate health promotion messages, or how mHealth technology might be leveraged to enhance existing mentoring models. Utilizing knowledge and training gained through this award in the areas of adolescent substance use, mHealth interventions, and analysis of dyadic and ?big? social media and smartphone data, the goal of the proposed study is to develop a prevention intervention in the form of a smartphone application (app), as well as training materials for using the app, to enhance existing mentoring models for highly vulnerable African American male adolescents in urban Baltimore. The training, professional development, and pilot data gained under this award will allow me to propose an R01 to conduct a naturalistic study or randomized controlled trial to measure effect sizes in the reduction of substance use and related health risk behaviors among mentored adolescent males. Support under a K award and the linked career development experiences will allow me to become an independent investigator focused on a new area of expertise?substance use prevention with urban American youth using mHealth?and to learn the skills required for successfully pursing NIH research funding. My long-term career goal is to answer the following research questions: 1) How can mentoring help improve health outcomes for at-risk adolescents and reduce health disparities in adulthood? and 2) How can mHealth be used in prevention intervention with this population? Fully understanding how to set up a systematic research program that intersects the fields of youth mentoring and effective mHealth intervention has great potential to lead me towards an innovative and productive independent research career in a new area. My intermediate career goals under this training grant are to focus work locally with African American adolescent males in Baltimore City, understand how technology-enhanced mentoring can serve as a universal prevention tool for urban male adolescents, build capacity to analyze dyadic data and data produced by social media and smartphone applications, and to develop collaborations with leading investigators in substance use prevention, youth mentoring, and mHealth research.